5KW Brushless Sailboat Kit

Please Enter: battery cell chemistry, amp hour rating, overall pack voltage, series cell count and arrangement
Please provide us with the specifications of your boat such as make, model, and displacement.
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Eliminate noxious diesel fumes, the cost of filling up at the pump, and enjoy your sailboat to the fullest with this DIY electric conversion Kit. The 5KW Brushless Kit featuring a Motenergy brushless motor and a 48V Sevcon Controller that can produce up to 5KW continuous and is often used to replace 10-15hp combustion engines. This system is best for boats up to 6,000 pounds displacement.

All our systems have reverse on-the-fly and contactor disable features. "Brushless" means that the motor does not have brushes that will wear out over time, nor will it be a dangerous source of ignition for on-board gas appliances. Larger boats may require a higher power AC or brushless motor. In the U.S. and Canada, brushed motors are only legal for marine use if onboard appliances and accessories use kerosene or diesel (not propane or gasoline) due to the potential for internal motor arcing.

The controller has a regen feature than can allow current to be put back into the batteries from the spinning prop while under sail. This depends on your sailing speed, prop design, and may not be possible in all applications, but is an adored feature for those who are able to use it.

Due to the high RPM of the brushless motor, we recommend the 5-10kW Gear Reduction to improve efficiency, provide proper torque, cooling, and help prevent cavitation. A typical reduction is 2:1, but this ratio will depend on the required prop RPM needed to reach hull speed. Ideal reduction will enable the motor to spin your prop at the hull speed RPM of your prop when the motor is spinning at its max RPM. We program the ME1718 in our 5kw kit to spin around 3000 rpm Max, at 48v. 

What batteries should you use? Most customers are happy with sealed, deep cycle lead acid, sourced locally to save on shipping. Use 4 in series to get 48v, with a 100 Amp Hour capacity minimum. Larger capacity will give a longer run time.

Those of you that are still in the "research phase" of your conversion should visit one of the Electric Boats Discussion Groups and talk to others who are doing or have already done electric conversions.

* Lead time is approximately one week

* Please describe your battery pack so that we can program your motor controller to match - then you won't need to ship it back to us. Minimum battery information includes cell chemistry, amp hour rating, overall pack voltage, series cell count and arrangement.

* If you choose not to use a gear reduction, a thrust bearing in line with the prop shaft is required, since most motors are not rated for axial/thrust loads on the shaft. 

* Before you pull your old engine, support the prop shaft for reference so you can properly align the new system.

* A heatsink for the controller is recommended by the manufacturer, and is included in the kit.

Included Components  (may vary based on kW rating and parts availability)

  • Motenergy ME1718 Sealed Brushless Motor.
  • Controller: 48V Sevcon G4827 (can also be programmed at 36v)
  • 827 Display for Sevcon
  • Throttle options - additional cost (see the Throttle page for more info): 
    • ET-134/126 directional throttle - recommended if you plan to use an existing throttle lever. The ET Actuator (included) connects to your existing throttle cable. Optons: ET-134 has a Neutral Detent, ET-126 has a Spring Return. 
    • Wigwag throttle lever - recommended if not reusing your existing lever
    • PB-8 throttle and Fwd/Rev Switch
  • Sealed Main Contactor
  • Key Switch
  • Finned Aluminum Heatsink
  • Every kit is individually bench tested
  • Complete wire harness with 10ft key and throttle cable lengths
  • Wiring instructions
Just let you know we have installed and tested the 5kw electric sailboat kit on our Catalina 27 and it runs perfectly, even better than what I expected. At 2000 RPM it can push the boat to around 3.8 kt, drawing only 34 amp, and at full throttle, it can push the boat to 5+ kt drawing 100 amp. We are very happy with the result. Thanks for providing the high quality products!
I've ended my 2nd full season of operation with my 5kW TS kit and am delighted to report another year of flawless operation and performance
Wanted to share my successes and learnings with the 5kw Thunderstruck kit, using the Sevcon GEN4/size 4 control and the ME1305 motor.

I replaced what appears to be the original 2.5hp GE/Taylor Dunn 36V series wound brushed motor. This motor achieved 5.5mph at 2kw turning 3000RPM, with v-belt reduction 3:1 driving an eight inch three blade composite propeller. The motor compartment is small and mounted high under the captain's seat midship, and is unventilated. The motor easily reached 180F underway for an hour and smelled like insulation and ozone. The speed control was a Salzer four three pole four position (+ off) that switched the battery configuration between 6S1P 36V to 3S2P 18V.

I expanded the battery bank to 48V with two additional 6V batteries, so the total capacity is about 10.5kwh, and is measured with a Bayrite chinesium watthour meter.

The new ME1305 was installed in a custom aluminum box that supports the NEMA C 143T size motor, with ducted cooling to the inlet side of the motor. The ducts pull air from an aluminum heatsink enclosure that the Sevcon controller is mounted to.

Testing on the Vermilion bayou was a little tricky due to river current, but to achieve the same propeller revolutions the motor and controller required 1200W watts to reach 3000RPM, so using 40% less energy than before. This, combined with less amperage at 48V brought my underway discharge rate from 55A to 25A, a major Peukert win. I went from 85MPGe to 131MPGe (2.5mi/kwh to 3.9mi/kwh), not accounting for any Peukert gains.

Despite having twice the available HP, I can't really increase my speed. My target was to put the ME1305 at its peak efficiency range of 3000-3500RPM, and the motor performance curve falls off quickly at the upper end of this speed range, so WOT gets me 3625RPM at 32A (1.5kW), which looks like about 6mph. At 70F ambient, the controller makes no apparent heat, and the motor skin reaches 90F after several hours and 18 miles of river travel.

Very happy with the kit build quality and value. My only suggestions would be for them to mark CW/CCW on the ET134 directional control, and smaller ring terminals for the Sevcon end of the cables.

Next modification will be propeller optimization.
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